1. Field of the Invention
The present invention relates to a method of manufacturing an armature of a rotary electric machine such as a direct current motor and to the armature manufactured by that method.
2. Description of Related Art
Recently, it has been becoming more important to develop automotive parts that are light in weight and small in size to reduce fuel consumption in an automobile vehicle and thereby to cope with the problem of global warming. One example of a light and small motor, which was invented by one of inventors of the present invention, is disclosed in JP-B2-2924605. In the armature of this motor, a conventional commutator is eliminated, and a commutator formed by part of the conductors disposed in an armature core is utilized. A pair of conductors consisting of an inner conductor and an outer conductor, each formed in a U-shape, is inserted in each slot formed in an armature core. Ends of the conductors are electrically and mechanically connected to thereby form an armature winding.
In the armature disclosed in JP-B2-2924605, however, the conductors are formed in a U-shape before they are inserted into the slots, and conductor portions disposed along the axial end surfaces of the armature core have to be skewed relative to the radial direction. The conductor has to be formed one by one using a complex transfer press, and therefore it has been difficult to further enhance the manufacturing speed. Further, it has not been easy to insert conductors, each having a U-shape and skewed ends, into the slots of the armature core. Therefore, there has been a certain limit in enhancing manufacturing speed in an automated assembling line.